Exodus 23:18
Thou shalt not offer the blood of my sacrifice with leavened bread; neither shall the fat of my sacrifice remain until the morning. Thou shalt not offer the blood of my sacrifice with leavened bread; neither shall the fat of my sacrifice remain until the morning.
The prohibition belongs to the instruction given to Moses on the mount in Exodus 19-24, among the statutes and judgments written in a book. The Teacher who gave those directions on Sinai is Christ Jesus speaking in human flesh. Within that body of instruction it stands among the directions for offerings, which called for presenting the first-fruits to the Lord and setting them apart for the priests. Those offerings taught Israel to put God first and to acknowledge Him as owner of field and flock and herd, while the people themselves were only stewards of what He had provided. The laws to which it belongs were given to guard against doing injustice and to guide dealings with one another.
The chapter holds truth and light and grace given from Sinai to be gathered up and carried out in practice in obedience to all of God's commandments. As an exalted requirement of God's law it is to be strictly obeyed, needed now just as verily as by the children of Israel in the days of Moses. Those who study the commandments and obey them with the heart enter open communion with God and are made kings and priests to God. Israel agreed with lifted voice and hands to meet these conditions of obedience, yet when Moses was away temptation came and they broke them by making the calf.